[cmd/telemetrygen] Use standard SDK configuration

[axw]

Component(s)

cmd/telemetrygen

Is your feature request related to a problem? Please describe.

Right now telemetrygen has various non-standard flags for configuring

• OTLP exporter: --otlp-endpoint, --otlp-header, --mtls, etc.
• SDK processors: --batch
• Resource attributes: --otlp-attributes, --service

Having non-standard configuration adds some cognitive overhead for users of the tool, as they must learn about the tool's specific configuration.

Describe the solution you'd like

I would like telemetrygen to support standard OTel SDK configuration: https://github.com/open-telemetry/opentelemetry-go-contrib/tree/main/config. That way end users have a single standard configuration format for the things described above.

When adding support for standard config, deprecate existing telemetrygen flags (except those that are specific to telemetrygen logic), and remove after a grace period.

Describe alternatives you've considered

Use https://github.com/open-telemetry/opentelemetry-go-contrib/tree/main/exporters/autoexport, which supports a standard set of env vars for configuring the SDK: https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/. This approach is being replaced by the config file approach mentioned above.

No response

Additional context

No response

[github-actions]

Pinging code owners:

• cmd/telemetrygen: @mx-psi @codeboten

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[mx-psi]

If we go down this route, should we support the OTel SDK configuration file instead? This is meant to be the replacement for environment variables

[axw]

@mx-psi sounds sensible. I'll rename the issue to be less about env vars, and more about "standard SDK configuration". What I really intended was for telemetrygen to follow an SDK standard.

I had a read of the config repo & OTEP, and couldn't find a clear answer: will there be no standard env vars in the long run? I certainly see the value in having a config file format, and understand that env vars are not expressive enough for all configuration, but I think there's also value in having standard default config that supports the current env vars for simple things such as the OTLP endpoint.

Has there been any discussion of having a default, built-in config in SDKs, e.g. https://github.com/open-telemetry/opentelemetry-configuration/blob/main/examples/sdk-migration-config.yaml?

Any pointers to relevant docs/specs/discussions would be appreciated.

[mx-psi]

@codeboten can probably answer these questions better than I can, but I believe this is meant to be (once stable) the recommended way of configuring the SDK. OTEP 225 has probably useful context

[axw]

@dmathieu pointed out to me that the environment variable specification is stable, so removing/breaking them would require a major version bump.

[mx-psi]

@axw Yes, the env var spec would still be supported, what I meant with the recommended way was the way that is used in all examples and documentation for example.

[github-actions]

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Pinging code owners:

• cmd/telemetrygen: @mx-psi @codeboten

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